1. Field of the Invention
This invention relates to an involuntary mandible oscillator system which forcibly opens and closes the lower jaw of the user for the purpose of rehabilitating abnormalities in and around the structure of the oral cavity.
2. Description of the Prior Art
A patient having temporomandibular joint ("TMJ") abnormalities in and around the structure of his oral cavity is asked to follow a rehabilitation regimen based on forcibly open and close his lower jaw. Such abnormalities may exist, for example, following arthroscopic procedures or TMJ reconstructive surgery.
The lower jaw forms part of the mandible. Jaw movement is the result of contraction of a group of muscles which perform their functions synergistically.
The mandibular elevators, which close the lower jaw, include the coordinated function of the masseter, temporal, and medial pterygoid muscles. The smooth and coordinated function of these muscles is essential for the proper occlusion of the teeth.
The mandibular depressors, which open the lower jaw, include the coordinated activity of the external pterygoid and the suprahyoid muscles. Protrusion of the mandible is performed by the masseter, internal pterygoid, and the external pterygoid muscles. Retrusion of the mandible is accomplished by the temporal an digastric muscles.
Soft tissue, e.g., scar tissue, cartilage, or any soft fibrous tissue, all hereinafter singularly or together called "tissue", can be described as a multiphasic structure consisting of cells, proteins, and proteoglycans entangled in a solid collagenous phase.
The proteoglycans swell in the presence of an electrolyte. The swelling pressure generated in the soft tissue is balanced by the tensile forces induced in the mesh of the collagen fibers in which the proteoglycans and cells are trapped. Movement of fluids into and out of the tissues is dependent on hydraulic permittivity and strain induced into the tissues.
Given a specific loading history imposed on a body of tissue, its physical properties will change dependent on the intensity of the applied loading and its direction. Tissue will change or remodel its volume, length, and mass from a reference structure to a new structure.
In particular, when a tensile strain history is imposed on tissue, the collagenous phase will remodel and align itself in a direction that is parallel to the principal direction of loading. In response to compressive loading, tissue remodels itself by increasing its proteoglycan content and aligns its collagenous phase in a plane perpendicular to the applied load.
Accordingly, loading can be directed and manipulated so as to accomplish specific therapeutic effects on the tissue. Thus, if properly administered, the involuntary total oscillation of the mandible, i.e., the automatic opening and closing of the mouth, following a prescribed rhythmic regimen, can induce strains within the oral tissue and surrounding structures that will result in enhanced healing and rapid pain reduction or suppression.
Such therapy will facilitate and accelerate the complete healing and rehabilitation of the tissue structures involved until the TMJ and the oral cavity are able to properly and adequately perform their various specific functions.
The rehabilitation process of the muscular structures of the oral cavity and of the TMJ, i.e., the actual muscle training and tissue healing, can be viewed as being voluntary, semi-voluntary, and involuntary.
A jaw exercising device, which is dependent solely on voluntary user participation, is described in U.S. Pat. No. 3,721,439. It is especially adapted for exercising the muscles of mastication in response to voluntary movement of the jaw by the user when biting upon a pair of intraoral, jaw-gripping plates. The voluntary jaw movement is resisted by a spring, hence inducing musculature development.
A mouth prop is described in U.S. Pat. No. 2,061,936. It is designed to prop open the jaws of a patient to gain access to the oral cavity with jaw-engaging bars that are spread apart by a threaded bolt on which a resilient coil spring is mounted. This prop has received wide acceptance for that purpose in the dental and medical professions.
In U.S. Pat. No. 4,700,695 is described a semi-voluntary system including an intraoral cam arrangement which is continuously driven by a motor for periodically opening (but not closing) the lower jaw.
This cam arrangement requires two intraoral cams, two maxillary tooth-engaging plates, two mandibular tooth-engaging plates, cam riding grooves within the mandibular plates, and a pair of cables for reciprocating both cams intraorally. The two intraoral cams, the two maxillary plates, the two mandibular tooth-engaging plates, and the pair of cables may require critical positioning, aligning and/or adjusting by an attendant in order to achieve proper bilateral jaw opening. Most importantly, this system assumes that the user's mandibular elevator muscles will voluntarily close the jaw.
But, when a user is under too much pain and swelling, he may be unable to voluntarily close the lower jaw, nor will his elevator muscles contract to close the mandibular jaw when they are under the influence of anesthetic agents or medication, or after they become detached during surgery. It normally takes about two to four weeks before the elevator muscles can regain their health or reattach to the mandible.
It is a primary object of this invention to provide a novel, totally involuntary jaw oscillator system, which is safe and substantially trouble-free, which allows a postoperative patient to administer to himself a prescribed continuous or intermittent motion protocol, in his home or hospital, thus avoiding dependence on an attendant for compliance with the protocol.
It is yet another object to provide a very effective, extraoral, electro-mechanical jaw oscillator system, which can be quickly and easily attached to and detached from the maxillary and mandibular jaws, and which is easily adapted for automatic operation under computer control.